Merge pull request #51 from jasongrout/instances

Take some of the magic out of traits by insisting traits be instances, not classes

traitlets/config/application.py

@@ -235,7 +235,7 @@ def _flags_changed(self, name, old, new):
     subapp = Instance('traitlets.config.application.Application', allow_none=True)
 
     # extra command-line arguments that don't set config values
-    extra_args = List(Unicode)
+    extra_args = List(Unicode())
 
 
     def __init__(self, **kwargs):

traitlets/tests/test_traitlets.py

@@ -11,6 +11,7 @@
 import re
 import sys
 from unittest import TestCase
+import warnings
 
 import nose.tools as nt
 from nose import SkipTest
@@ -140,7 +141,7 @@ def test_metaclass(self):
         self.assertEqual(type(HasTraits), MetaHasTraits)
 
         class A(HasTraits):
-            a = Int
+            a = Int()
 
         a = A()
         self.assertEqual(type(a.__class__), MetaHasTraits)
@@ -191,8 +192,8 @@ def notify2(self, name, old, new):
     def test_notify_all(self):
 
         class A(HasTraits):
-            a = Int
-            b = Float
+            a = Int()
+            b = Float()
 
         a = A()
         a.on_trait_change(self.notify1)
@@ -215,8 +216,8 @@ class A(HasTraits):
     def test_notify_one(self):
 
         class A(HasTraits):
-            a = Int
-            b = Float
+            a = Int()
+            b = Float()
 
         a = A()
         a.on_trait_change(self.notify1, 'a')
@@ -229,10 +230,10 @@ class A(HasTraits):
     def test_subclass(self):
 
         class A(HasTraits):
-            a = Int
+            a = Int()
 
         class B(A):
-            b = Float
+            b = Float()
 
         b = B()
         self.assertEqual(b.a,0)
@@ -245,10 +246,10 @@ class B(A):
     def test_notify_subclass(self):
 
         class A(HasTraits):
-            a = Int
+            a = Int()
 
         class B(A):
-            b = Float
+            b = Float()
 
         b = B()
         b.on_trait_change(self.notify1, 'a')
@@ -265,7 +266,7 @@ class B(A):
     def test_static_notify(self):
 
         class A(HasTraits):
-            a = Int
+            a = Int()
             _notify1 = []
             def _a_changed(self, name, old, new):
                 self._notify1.append((name, old, new))
@@ -278,7 +279,7 @@ def _a_changed(self, name, old, new):
         self.assertTrue(('a',0,10) in a._notify1)
 
         class B(A):
-            b = Float
+            b = Float()
             _notify2 = []
             def _b_changed(self, name, old, new):
                 self._notify2.append((name, old, new))
@@ -303,7 +304,7 @@ def callback4(name, old, new, obj):
             self.cb = (name, old, new, obj)
 
         class A(HasTraits):
-            a = Int
+            a = Int()
 
         a = A()
         a.on_trait_change(callback0, 'a')
@@ -376,8 +377,8 @@ class TestHasTraits(TestCase):
 
     def test_trait_names(self):
         class A(HasTraits):
-            i = Int
-            f = Float
+            i = Int()
+            f = Float()
         a = A()
         self.assertEqual(sorted(a.trait_names()),['f','i'])
         self.assertEqual(sorted(A.class_trait_names()),['f','i'])
@@ -399,8 +400,8 @@ class A(HasTraits):
 
     def test_traits(self):
         class A(HasTraits):
-            i = Int
-            f = Float
+            i = Int()
+            f = Float()
         a = A()
         self.assertEqual(a.traits(), dict(i=A.i, f=A.f))
         self.assertEqual(A.class_traits(), dict(i=A.i, f=A.f))
@@ -665,7 +666,7 @@ class TestThis(TestCase):
 
     def test_this_class(self):
         class Foo(HasTraits):
-            this = This
+            this = This()
 
         f = Foo()
         self.assertEqual(f.this, None)
@@ -771,7 +772,7 @@ def tearDown(self):
 
 class AnyTrait(HasTraits):
 
-    value = Any
+    value = Any()
 
 class AnyTraitTest(TraitTestBase):
 
@@ -974,7 +975,7 @@ class TestTCPAddress(TraitTestBase):
 
 class ListTrait(HasTraits):
 
-    value = List(Int)
+    value = List(Int())
 
 class TestList(TraitTestBase):
 
@@ -1036,7 +1037,7 @@ class TestUnionListTrait(HasTraits):
 
 class LenListTrait(HasTraits):
 
-    value = List(Int, [0], minlen=1, maxlen=2)
+    value = List(Int(), [0], minlen=1, maxlen=2)
 
 class TestLenList(TraitTestBase):
 
@@ -1071,7 +1072,7 @@ def coerce(self, value):
     def test_invalid_args(self):
         self.assertRaises(TypeError, Tuple, 5)
         self.assertRaises(TypeError, Tuple, default_value='hello')
-        t = Tuple(Int, CBytes, default_value=(1,5))
+        t = Tuple(Int(), CBytes(), default_value=(1,5))
 
 class LooseTupleTrait(HasTraits):
 
@@ -1093,12 +1094,12 @@ def coerce(self, value):
     def test_invalid_args(self):
         self.assertRaises(TypeError, Tuple, 5)
         self.assertRaises(TypeError, Tuple, default_value='hello')
-        t = Tuple(Int, CBytes, default_value=(1,5))
+        t = Tuple(Int(), CBytes(), default_value=(1,5))
 
 
 class MultiTupleTrait(HasTraits):
 
-    value = Tuple(Int, Bytes, default_value=[99,b'bottles'])
+    value = Tuple(Int(), Bytes(), default_value=[99,b'bottles'])
 
 class TestMultiTuple(TraitTestBase):
 
@@ -1675,3 +1676,34 @@ class C(HasTraits):
 
     c = C(t='b')
     assert c.t == 'b'
+
+
+class TestTraitType(TestCase):
+
+    def test_trait_types_deprecated(self):
+        with warnings.catch_warnings():
+            warnings.filterwarnings('error')
+            with self.assertRaises(DeprecationWarning):
+                class C(HasTraits):
+                    t = Int
+
+    def test_trait_types_list_deprecated(self):
+        with warnings.catch_warnings():
+            warnings.filterwarnings('error')
+            with self.assertRaises(DeprecationWarning):
+                class C(HasTraits):
+                    t = List(Int)
+
+    def test_trait_types_tuple_deprecated(self):
+        with warnings.catch_warnings():
+            warnings.filterwarnings('error')
+            with self.assertRaises(DeprecationWarning):
+                class C(HasTraits):
+                    t = Tuple(Int)
+
+    def test_trait_types_dict_deprecated(self):
+        with warnings.catch_warnings():
+            warnings.filterwarnings('error')
+            with self.assertRaises(DeprecationWarning):
+                class C(HasTraits):
+                    t = Dict(Int)

traitlets/traitlets.py

@@ -531,6 +531,7 @@ def __new__(mcls, name, bases, classdict):
                 v.name = k
             elif inspect.isclass(v):
                 if issubclass(v, TraitType):
+                    warn("Traits should be given as instances, not types (for example, `Int()`, not `Int`)", DeprecationWarning, stacklevel=2)
                     vinst = v()
                     vinst.name = k
                     classdict[k] = vinst
@@ -1524,6 +1525,8 @@ def __init__(self, trait=None, default_value=None, **metadata):
             raise TypeError('default value of %s was %s' %(self.__class__.__name__, default_value))
 
         if is_trait(trait):
+            if isinstance(trait, type):
+                warn("Traits should be given as instances, not types (for example, `Int()`, not `Int`)", DeprecationWarning)
             self._trait = trait() if isinstance(trait, type) else trait
         elif trait is not None:
             raise TypeError("`trait` must be a Trait or None, got %s" % repr_type(trait))
@@ -1676,7 +1679,7 @@ def __init__(self, *traits, **metadata):
 
         Create a fixed-type tuple with Traits:
 
-        ``t = Tuple(Int, Str, CStr)``
+        ``t = Tuple(Int(), Str(), CStr())``
 
         would be length 3, with Int,Str,CStr for each element.
 
@@ -1717,6 +1720,8 @@ def __init__(self, *traits, **metadata):
 
         self._traits = []
         for trait in traits:
+            if isinstance(trait, type):
+                warn("Traits should be given as instances, not types (for example, `Int()`, not `Int`)", DeprecationWarning, stacklevel=2)
             t = trait() if isinstance(trait, type) else trait
             self._traits.append(t)
 
@@ -1796,6 +1801,8 @@ def __init__(self, trait=None, traits=None, default_value=Undefined,
 
         # Case where a type of TraitType is provided rather than an instance
         if is_trait(trait):
+            if isinstance(trait, type):
+                warn("Traits should be given as instances, not types (for example, `Int()`, not `Int`)", DeprecationWarning, stacklevel=2)
             self._trait = trait() if isinstance(trait, type) else trait
         elif trait is not None:
             raise TypeError("`trait` must be a Trait or None, got %s" % repr_type(trait))